Counterfeits of articles (for example, goods and garments), which are produced by copying appearances of authentic ones, are being sold, and they cause problems. Under these circumstances, in order to ensure performance, reliability and security of articles and to maintain the worthiness of the brands of articles, techniques for verifying the authenticity of the article are required.
A method in which printing is performed on an article by using a special ink or a method in which a chip having special reflection characteristics is applied onto an article may be used as a technique for verifying the authenticity of the article.
In the above method using the special ink printed on an article, for example, a predetermined character or a figure is printed on an article by using an ink, which is fluorescent under ultraviolet light, as the above ink. When ultraviolet light is irradiated on the article, the character or the figure becomes visible on the article, so that the authenticity of the article can be determined. For example, an ink having particles of a magnetic material or magnetized particles mixed therewith may be applied on an article, and the authenticity of the article can be verified by using magnetic sensors.
In the above method using the chip having special reflection characteristics, a chip using optical characteristics of a cholesteric liquid crystal formed thereon is used as the above chip. For example, this technique using optical characteristics of the cholesteric liquid crystal is disclosed in Japanese Unexamined Patent Application Publication No. H4-144796. A seal having a hologram function is known.
In a method for verifying the authenticity of garments, there is known a technique in which an micro-embroidery which cannot be seen with the unaided eye is formed and a pattern thereof is verified by using a magnifying lens. In addition, there is known a technique in which an embroidery is formed by using a fiber having a fluorescent function and a pattern thereof becomes visible by irradiating a light (for example, ultraviolet light) in a predetermined wavelength range.